|Mongolia is high, cold, and dry. It has an extreme continental climate with long, cold winters and short summers, during which most precipitation falls. The country averages 257 cloudless days a year, and it is usually at the center of a region of high atmospheric pressure. Precipitation is highest in the north, which averages 200 to 350 millimeters (7.9 to 13.8 in) per year, and lowest in the south, which receives 100 to 200 millimeters (3.9 to 7.9 in). The extreme south is the Gobi Desert, some regions of which receive no precipitation at all in most years. The name Gobi is a Mongol word meaning desert, depression, salt marsh, or steppe, but which usually refers to a category of arid rangeland with insufficient vegetation to support marmots but with enough to support camels. Mongols distinguish Gobi from desert proper, although the distinction is not always apparent to outsiders unfamiliar with the Mongolian landscape. Gobi rangelands are fragile and are easily destroyed by overgrazing, which results in expansion of the true desert, a stony waste where not even Bactrian camels can survive.
Average temperatures over most of the country are below freezing from November through March and are about freezing in April and October. January and February averages of −20 °C (−4 °F) are common, with winter nights of −40 °C (−40 °F) occurring most years. Summer extremes reach as high as 38 °C (100.4 °F) in the southern Gobi region and 33 °C (91.4 °F) in Ulaanbaatar. Most of Mongolia is covered by discontinuous permafrost (grading to continuous at high altitudes), which makes construction, road building, and mining difficult. All rivers and freshwater lakes freeze over in the winter, and smaller streams commonly freeze to the bottom. Ulaanbaatar lies at 1,351 meters (4,432 ft) above sea level in the valley of the Tuul River. Located in the relatively well-watered north, it receives an annual average of 310 millimetres (12.2 in) of precipitation, almost all of which falls in July and in August. Ulaanbaatar has an average annual temperature of −2.9 °C (26.8 °F) and a frost-free period extending on the average from mid-June to late August. (Source: Wikipedia)